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  Internal and External Serrations
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A serrated shaft is a series of adjacent triangular projections which are named teeth and are formed around its periphery. The theoretical major diameter is that of a circle passing through the apices of the fundamental triangles formed by the flanks of the teeth, the theoretical minor diameter is that of a circle passing through the points where the bases of the fundamental triangles touch. The effective diameter of the serrated shaft is that of a circle midway between the theoretical major and minor diameters. Similarly a serrated hole comprises of a series of adjacent triangular teeth from which fundamental triangles are formed. Serrations provide a means of transferring drive from one member to another with the stress around the join evenly distributed.

There are several uses but are not as popular nowadays. They are used in aircraft and especially the fine pitch ones can be used in mechanisms for adjusting the timing between important features.

The tooling we have enable us to cover many sizes of internal and external serrations including the old B.S. A.19 fine and coarse pitch and B.S 2059-1953.


Hewitt & Topham Limited, Royd Way, Keighley, West Yorkshire BD21 3LG United Kingdom
Tel: +44 (0) 1535 602587  Fax : +44 (0) 1535 680587  Email: sales@hewitt-topham.co.uk


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